package com.movementinsome.kernel.camera;

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.util.FloatMath;
import android.view.MotionEvent;
import android.widget.ImageView;

public class ImageTouchView extends ImageView {

    private PointF startPoint = new PointF(); 
    private Matrix matrix = new Matrix(); 
    private Matrix currentMaritx = new Matrix(); 
                                                                                                                                                                                                                                                                                                                                                                                                                             
    private int mode = 0;//用于标记模式 
    private static final int DRAG = 1;//拖动 
    private static final int ZOOM = 2;//放大 
    private float startDis = 0; 
    private PointF midPoint;//中心点 
                                                                                                                                                                                                                                                                                                                                                                                                                             
    /** 
     * 默认构造函数 
     * @param context 
     */
    public ImageTouchView(Context context){ 
        super(context); 
    } 
    /** 
     * 该构造方法在静态引入XML文件中是必须的 
     * @param context 
     * @param paramAttributeSet 
     */
    public ImageTouchView(Context context,AttributeSet paramAttributeSet){ 
        super(context,paramAttributeSet); 
    } 
                                                                                                                                                                                                                                                                                                                                                                                                                             
    public boolean onTouchEvent(MotionEvent event) { 
        switch (event.getAction() & MotionEvent.ACTION_MASK) { 
        case MotionEvent.ACTION_DOWN: 
            mode = DRAG; 
            currentMaritx.set(this.getImageMatrix());//记录ImageView当期的移动位置 
            startPoint.set(event.getX(),event.getY());//开始点 
            break; 
        case MotionEvent.ACTION_MOVE://移动事件 
                                                                                                                                                                                                                                                                                                                                                                                                                              
            if (mode == DRAG) {//图片拖动事件 
                float dx = event.getX() - startPoint.x;//x轴移动距离 
                float dy = event.getY() - startPoint.y; 
                matrix.set(currentMaritx);//在当前的位置基础上移动 
                matrix.postTranslate(dx, dy); 
                                                                                                                                                                                                                                                                                                                                                                                                                                        
            } else if(mode == ZOOM){//图片放大事件 
                float endDis = distance(event);//结束距离 
                if(endDis > 10f){ 
                    float scale = endDis / startDis;//放大倍数 
                    //Log.v("scale=", String.valueOf(scale)); 
                    matrix.set(currentMaritx); 
                    matrix.postScale(scale, scale, midPoint.x, midPoint.y); 
                } 
                                                                                                                                                                                                                                                                                                                                                                                                                                        
                                                                                                                                                                                                                                                                                                                                                                                                                                        
            } 
            break; 
                                                                                                                                                                                                                                                                                                                                                                                                                                     
        case MotionEvent.ACTION_UP: 
            mode = 0; 
            break; 
        //有手指离开屏幕，但屏幕还有触点(手指) 
        case MotionEvent.ACTION_POINTER_UP: 
            mode = 0; 
            break; 
        //当屏幕上已经有触点（手指）,再有一个手指压下屏幕 
        case MotionEvent.ACTION_POINTER_DOWN: 
            mode = ZOOM; 
            startDis = distance(event); 
                                                                                                                                                                                                                                                                                                                                                                                                                                     
            if(startDis > 10f){//避免手指上有两个茧 
                midPoint = mid(event); 
                currentMaritx.set(this.getImageMatrix());//记录当前的缩放倍数 
            } 
                                                                                                                                                                                                                                                                                                                                                                                                                                     
            break; 
        } 
        this.setImageMatrix(matrix); 
        return true; 
    } 
                                                                                                                                                                                                                                                                                                                                                                                                                             
    /** 
     * 两点之间的距离 
     * @param event 
     * @return 
     */
    private static float distance(MotionEvent event){ 
        //两根线的距离 
        float dx = event.getX(1) - event.getX(0); 
        float dy = event.getY(1) - event.getY(0); 
        return (float)Math.sqrt(dx*dx + dy*dy);
    } 
    /** 
     * 计算两点之间中心点的距离 
     * @param event 
     * @return 
     */
    private static PointF mid(MotionEvent event){ 
        float midx = event.getX(1) + event.getX(0); 
        float midy = event.getY(1) - event.getY(0); 
                                                                                                                                                                                                                                                                                                                                                                                                                                 
        return new PointF(midx/2, midy/2); 
    } 
}
